Abstract : Living airborne microflora have at least two properties that laboratory microflora do not. First, each airborne cell has survived innumerable changes in environment. Second, each airborne cell maintains its own life in a 'dry' and radiation-filled environment where enzymatic or other biochemical reactions, if not absent, are minimal. Studies of the survival and maintenance of life in conditions like that of the upper atmosphere might be accomplished either by surveying the atmosphere for its living content, or by holding suitable organisms in controlled atmospheric conditions and studying their viability for the purpose of extrapolating to natural conditions. This paper is concerned with the latter approach. General techniques employed in study of microorganisms in contact with the atmosphere are: (1) Aerobiological techniques, wherein cultures are aerosolized into chambers under controlled conditions, air is sampled, and survival is studied. (2) Freeze-drying techniques, wherein cultures are frozen at various temperatures and then placed into a high vacuum until the moisture content has been reduced to between five percent and some unknown lower limit. (3) Surface drying techniques (desiccation), wherein cultures are painted onto surfaces and then exposed to a variety of atmospheric conditions. (Author)